{
    const city = {
        name: 'Hangzhou',
        location: 'South',
    }

    console.log('name' in city)  // => true
    console.log('Hangzhou' in city)  // => false

    console.log(Object.keys(city))  // => ["name", "location"]
    console.log(Object.values(city)) // => ["Hangzhou", "South"]
}

{
    class City {
        name = 'Hangzhou'
        location = 'South'
    }

    console.log('name' in City)  // => true
    console.log('Hangzhou' in City) // => false

    console.log(Object.keys(City))  // => []
    console.log(Object.values(City))  // => []

    console.log(Object.keys(new City())) // => ["name", "location"]
    console.log(Object.values(new City())) // => ["Hangzhou", "South"]
}
